Quantitation of type I, III, and V collagens in human tissue samples by high-performance liquid chromatography of selected cyanogen bromide peptides

Fabrication and performance evaluation of PLCL-hCOLIII small-diameter vascular grafts crosslinked with procyanidins

Cardiovascular disease has become one of the main causes of death. It is the common goal of researchers worldwide to develop small-diameter vascular grafts to meet clinical needs. Collagen is a valuable biomaterial that has been used in the preparation of vascular grafts and has shown good results. Recombinant humanized collagen (RHC) has the advantages of clear chemical structure, batch stability, no virus hazard and low immunogenicity compared with animal-derived collagen, which can be developed as vascular materials. In this study, Poly (l-lactide- ε-caprolactone) with l-lactide/ε-caprolactone (PLCL) and type III recombinant humanized collagen (hCOLIII) were selected as raw materials to prepare vascular grafts, which were prepared by the same-nozzle electrospinning apparatus. Meanwhile, procyanidin (PC), a plant polyphenol, was used to cross-link the vascular grafts. The physicochemical properties and biocompatibility of the fabricated vascular grafts were investigated by comparing with glutaraldehyde (GA) crosslinked vascular grafts and pure PLCL grafts. Finally, the performance of PC cross-linked PLCL-hCOLIII vascular grafts were evaluated by rabbit carotid artery transplantation model. The results indicate that the artificial vascular grafts have good cell compatibility, blood compatibility, and anti-calcification performance, and can remain unobstructed after 30 days carotid artery transplantation in rabbits. The grafts also showed inhibitory effects on the proliferation of SMCs and intimal hyperplasia, demonstrating its excellent performance as small diameter vascular grafts.

The Correlation Between Collagen Types and Ultrasound Feature Score in Evaluating the Vulnerability of Carotid Artery Plaque

Objectives: To investigate whether ultrasound score has clinical value in identifying carotid artery-vulnerable plaque and the impacts of collagen distribution on the stability of plaque.

Materials and Methods: Standard carotid artery ultrasound examinations were performed in 51 patients with carotid artery plaques before carotid endarterectomy. Hematoxylin-eosin staining and Sirius red–picric acid staining of plaque sections were performed to analyze the pathological features and collagen distribution. All plaques were classified into vulnerable and stable groups by pathological features. Ultrasound scores, cap thickness, and the ratios of different collagen types were recorded and analyzed between two groups and different parts of plaques.

Results: Ultrasound scores of the vulnerable group were higher than those of the stable group (4.35 ± 1.23 vs. 2.09 ± 1.04, P = 0.001). AUC was 0.894 (best cutoff point three) in differentiating vulnerable and stable plaques. Compared with the stable group, the fibrous caps of the vulnerable group were thinner (P = 0.012); the area ratios of collagen type I to all collagen in the vulnerable group were lower (P = 0.033); however, the area ratios of collagen type IV to all collagen were higher (P = 0.026). Compared with downstream shoulders, the ultrasound scores of upstream shoulders of plaque were higher (P = 0.001), the fibrous caps of upstream shoulders were thinner (P = 0.001), and the area ratios of collagen type I to all collagen were lower (P = 0.022).

Conclusion: Ultrasound score could have a clinical value in identifying vulnerable carotid artery plaque, and the collagen distribution could impact the stability of plaques, especially collagen type I and type IV. The results also prompted that the upstream shoulders were more vulnerable than the downstream shoulders.

Platelet derived growth factor-A (Pdgf-a) gene transfer modulates scar composition and improves left ventricular function after myocardial infarction

BACKGROUND

Novel therapies that can limit or reverse damage caused by myocardial infarction (MI) could ease the increasing burden of heart failure. In this regard Platelet Derived Growth Factor (PDGF) has been previously shown to contribute to cardiac repair after MI. Here, we use a rodent model of MI and recombinant adeno-associated virus 9 (rAAV9)-mediated gene transfer to overexpress Pdgf-a in the injured heart and assess its therapeutic potential.

METHODS AND RESULTS

Sprague Dawley rats underwent temporary occlusion of the left anterior descending coronary artery, followed immediately by systemic delivery of 1 × 10^11 vector genomes of either rAAV9 Pdgf-a or rAAV9 Empty vector (control). At day 28 post-MI echocardiography showed significantly improved left ventricular (LV) function (fractional shortening) after rAAV9 Pdgf-a (0.394 ± 0.019%) treatment vs control (0.304 ± 0.018%). Immunohistochemical analysis demonstrated significantly increased capillary and arteriolar density in the infarct border zone of rAAV9 Pdgf-a treated hearts together with a significant reduction in infarct scar size (rAAV9 Pdgf-a 6.09 ± 0.94% vs Empty 12.45 ± 0.92%). Western blot and qPCR analyses confirmed overexpression of PDGF-A and showed upregulation of smooth muscle alpha actin (Acta2), collagen type III alpha 1 (Col3a1) and lysyl oxidase (Lox) genes in rAAV9 Pdgf-a treated infarcts.

CONCLUSION

Overexpression of Pdgf-a in the post-MI heart can modulate scar composition and improve LV function. Our study highlights the potential of rAAV gene transfer of Pdgf-a as a cardio-reparative therapy.

The collαgen III fibril has a "flexi-rod" structure of flexible sequences interspersed with rigid bioactive domains including two with hemostatic roles

Collagen III is critical to the integrity of blood vessels and distensible organs, and in hemostasis. Examination of the human collagen III interactome reveals a nearly identical structural arrangement and charge distribution pattern as for collagen I, with cell interaction domains, fibrillogenesis and enzyme cleavage domains, several major ligand-binding regions, and intermolecular crosslink sites at the same sites. These similarities allow heterotypic fibril formation with, and substitution by, collagen I in embryonic development and wound healing. The collagen III fibril assumes a "flexi-rod" structure with flexible zones interspersed with rod-like domains, which is consistent with the molecule's prominence in young, pliable tissues and distensible organs. Collagen III has two major hemostasis domains, with binding motifs for von Willebrand factor, α2β1 integrin, platelet binding octapeptide and glycoprotein VI, consistent with the bleeding tendency observed with COL3A1 disease-causing sequence variants.

Effects of collagen deposition on passive and active mechanical properties of large pulmonary arteries in hypoxic pulmonary hypertension

Proximal pulmonary artery (PA) stiffening is a strong predictor of mortality in pulmonary hypertension. Collagen accumulation is mainly responsible for PA stiffening in hypoxia-induced pulmonary hypertension (HPH) in mouse models. We hypothesized that collagen cross-linking and the type I isoform are the main determinants of large PA mechanical changes during HPH, which we tested by exposing mice that resist type I collagen degradation (Col1a1[Formula: see text] and littermate controls (Col1a1[Formula: see text] to hypoxia for 10 days with or without [Formula: see text]-aminopropionitrile (BAPN) treatment to prevent cross-link formation. Static and dynamic mechanical tests were performed on isolated PAs with smooth muscle cells (SMC) in passive and active states. Percentages of type I and III collagen were quantified by histology; total collagen content and cross-linking were measured biochemically. In the SMC passive state, for both genotypes, hypoxia tended to increase PA stiffness and damping capacity, and BAPN treatment limited these increases. These changes were correlated with collagen cross-linking ([Formula: see text]). In the SMC active state, hypoxia increased PA dynamic stiffness and BAPN had no effect in Col1a1[Formula: see text] mice ([Formula: see text]). PA stiffness did not change in Col1a1[Formula: see text] mice. Similarly, damping capacity did not change for either genotype. Type I collagen accumulated more in Col1a1[Formula: see text] mice, whereas type III collagen increased more in Col1a1[Formula: see text] mice during HPH. In summary, PA passive mechanical properties (both static and dynamic) are related to collagen cross-linking. Type I collagen turnover is critical to large PA remodeling during HPH when collagen metabolism is not mutated and type III collagen may serve as a reserve.

Preparative procedures and purity assessment of collagen proteins

Collagens represent a large family (25 members identified so far) of closely related proteins. While the preparative procedures for the members that are ubiquitous and present in tissues in large quantities (typically fibre and network forming collagens types I, II, III, IV and V) are well established, the procedures for more recently discovered minor collagen types, namely those possessing large non-collagenous domain(s) in their molecule, are mostly micropreparative and for some collagenous proteins even do not exist. The reason is that the proof of their existence is based on immunochemical staining of tissue slices and nucleic database searching. Methods of preparation and identification of constituting alpha-polypeptide chains as well as collagenous and non-collagenous domains are also reviewed. Methods for revealing non-enzymatic posttranslational modifications (particularly of the fibre forming collagen types) are briefly described as well.

Biochemical structural analysis of the lantibiotic mutacin II

Mutacin II is a post-translationally modified lantibiotic peptide secreted by Streptococcus mutans T8, which inhibits the energy metabolism of sensitive cells. The deduced amino acid sequence of promutacin II is NRWWQGVVPTVSYECRMNSWQHVFTCC, which is capable of forming three thioether bridges. It was not obvious, however, how the three thioether bridges are organized. To examine the bridging, the cyanogen bromide cleavage products of mutacin II and its variants generated by protein engineering, C15A, C26A, and C15A/C26A, were analyzed by mass spectrometry. Analysis of the wild type molecule and the C15A variant excluded several possibilities and also indicated a high fidelity of formation of the thioether bridges. This allowed us to further resolve the structure by analysis (mass spectrometry and tandem mass spectrometry) of the cyanogen bromide cleavage fragments of the C26A and C15A/C26A mutants. Nuclear magnetic resonance analysis established the presence of one and two dehydrobutyrine residues in mutacin II and the C15A variant, respectively, thus yielding the final structure. The results of this investigation showed that the C-terminal part contains three thioether bridges connecting Cys residues 15, 26, and 27 to Ser/Thr residues 10, 12 and 19, respectively, with Thr(25) being modified to dehydrobutyrine.

Post-translational non-enzymatic modification of proteins. II. Separation of selected protein species after glycation and other carbonyl-mediated modifications

There are two strategies applicable to revealing non-enzymatic post-translational modifications of proteins; while assaying of the hydrolytically stable adducts was the subject of our previous communication [1], here we attempted to review separation technologies for the unfragmented modified proteins. There are a few standard procedures used for this purpose, namely Laemmli gel electrophoresis, different modes of gel permeation chromatography and boronate affinity chromatography. The latter approach makes use of the vicinal hydroxy groups present in glycated proteins. Some (but not all) arising adducts exhibit typical fluorescence which can be exploited for detection. In most cases fluorescence is measured at 370/440 nm for the so-called advanced glycation products or at 335/385 nm for the only so far well characterized glycation marker (pentosidine). Some indication exists that, e.g., synchronous fluorescence detection will probably in the future add to the selectivity and allow the distinction of the different adducts arising during non-enzymatic post-translational modifications (glycation). The proteins reviewed are serum albumin, collagen and lens proteins while glycation of hemoglobin is the subject of another review within the present volume.

Biochemical and molecular homogeneity in the patellar tendon of the immature pig

Patellar tendon is widely used for reconstruction of the anterior cruciate ligament. However, few studies have investigated the tendon's homogeneity, a characteristic often assumed of it in experiments. In this study, the assumption that the patellar tendon is homogeneous was tested by dividing the central half of the tendon into six sections along its length and width and comparing commonly measured biochemical parameters and patterns of gene expression among these sections. No significant differences were found between the sections for any of the studied parameters: water content (p > 0.5), DNA content (p > 0.9), total collagen content (p > 0.8), amount of type I collagen (p > 0.7) or type-III collagen (p > 0.7), or expression of mRNA (p > 0.9). For all parameters, the minimum power value for statistical analyses was greater than 0.80. It was concluded that the central half of the tendon is homogeneous in terms of all of the measured parameters. The results provide important information for the many experiments that sample part of the patellar tendon to infer the characteristics of the whole tendon, e.g., biopsy studies.

Quantitation of collagen types I, III and V in tissue slices by capillary electrophoresis after cyanogen bromide solubilization

A method for the determination of the proportions of major fiber-forming collagens (types I, III and V) in soft connective tissue was elaborated. The method is based on the release of insoluble collagen by CNBr with subsequent separation of the arising peptides. For routine application the peptides are separated by capillary electrophoresis (50 mM phosphate pH 2.5, 15 kV, 50 degrees C, 70/60 cm x 70 microns I.D. capillary with UV detection at 200 nm). Quantitation of collagen type I can be done either on the basis of spiking the sample with a peptide mixture obtained from a known amount of collagen type I, or by spiking the sample with an equimolar mixture of the two peptides [alpha 1(I)CB2 and alpha 1(I)CB4] (constituting a fused peak) along with alpha 1(III)CB2 and alpha 1(V)CB1. Compared to the previously published methods the procedure is faster and does not require isolation of marker peptides by tedious chromatographic procedures in a preceding preparatory step. Good results are obtained within a wide range of run buffer concentrations and applied voltages; conversely, intensive cleaning of the capillary after every three runs is recommended with a new capillary after 20-30 runs.

Effect of physical crosslinking methods on collagen-fiber durability in proteolytic solutions

We previously demonstrated that ultraviolet (UV) or dehydrothermal (DHT) crosslinking partially denatured fibers extruded from an insoluble type I collagen dispersion. In this study denaturation effects were evaluated by measuring collagen-fiber sensitivity to trypsin. Shrinkage-temperature measurements and sensitivity to collagenase served as indices of crosslinking. UV or DHT crosslinking increased the collagen-fiber shrinkage temperature, resistance to degradation in collagenase, and durability under load in collagenase. However, in trypsin solutions, solubility was significantly increased for UV (approximately 11%) or DHT (approximately 15%) crosslinked fibers compared with uncrosslinked fibers (approximately 4%). Size-exclusion chromatography indicated that no intact collagen alpha-chains were present in the soluble fraction of fibers exposed to trypsin (MW < 1 kD). Interestingly, UV-crosslinked collagen fibers remained intact an order of magnitude longer (4840 +/- 739 min) than DHT-crosslinked (473 +/- 39 min) or uncrosslinked (108 +/- 53 min) fibers when placed under load in trypsin solutions. These data indicate that mechanical loading during incubation in a trypsin solution measures denaturation effects not detected by the trypsin-solubility assay. Our results suggest that DHT-crosslinked collagen fibers should not be used as load-bearing implants. UV-crosslinked fibers may retain more native structure and should exhibit greater resistance to nonspecific proteases in vivo.

The intrinsic and extrinsic ligaments of the wrist. A correlation of collagen typing and histologic appearance

20 fresh frozen human wrist specimens were dissected. Gross and histological examination and biochemical evaluation were performed on the intrinsic ligaments (scapho-lunate and luno-triquetral) and extrinsic ligaments (radio-scapho-capitate and radio-lunate). All ligaments were observed to have longitudinal collagen bundles. The intrinsic ligaments had large amounts of fibrocartilage near insertions and no elastin, while the extrinsic ligaments had little fibrocartilage and sparse amounts of elastin. The intrinsic ligaments were noted to have significantly more collagen Type 3 (41%) than the extrinsic ligaments (19%). These findings suggest that structural differences between the intrinsic and extrinsic ligaments of the wrist may in part account for the biomechanical observations that the intrinsic ligaments are stronger and elongate further prior to failure than the extrinsic ligaments.

A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association

This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesion progression. The initial (type 1) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. Type III is the intermediate stage between type II and type IV (atheroma, a lesion that is potentially symptom-producing). In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc).

A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association

This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesions progression. The initial (type I) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. Type III is the intermediate stage between type II and type IV (atheroma, a lesion that is potentially symptom-producing). In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc).

Immunoquantification of type I, III, IV and V collagen in small samples of human lung parenchyma

The involvement of collagen in pathological conditions underscores the need for sensitive, collagen type-specific assays. A method for the quantification of different types of collagen in lung has been developed. Human lung parenchyma is digested with cyanogen bromide which results in almost complete solubilization of collagen to type-specific collagen peptides. The peptides are quantified using inhibition enzyme immunoassays with type-specific antibodies. The 50% inhibition value for the type I collagen assay is 1 microgram type I collagen peptides, for the type III collagen assay 350 ng type III collagen peptides, for the type IV collagen 200 ng type IV collagen peptides, and for the type V collagen assay 50 ng type V collagen peptides. Using less than 1 mg lyophilized human parenchymal lung tissue it was established that the amount of collagen/mg dry tissue (+/- SD, n = 10) is 84.6 +/- 16.1 micrograms for type I collagen, 26.6 +/- 10.3 micrograms for type III collagen, 9.6 +/- 2.0 micrograms for type IV collagen and 1.8 +/- 0.3 micrograms for type V collagen. The procedure is useful for the quantification of different types of collagen, including minor collagens, and requires only minimal sample preparation.

Definitive proof of endothelialization of a Dacron arterial prosthesis in a human being

A 10 mm woven Dacron axillofemoral bypass graft was removed from a 65-year-old patient during redo surgery after an implant period of 26 months, because of a large seroma that surrounded the entire length of the graft. Tissue blocks were taken from representative areas along the entire length of the graft surface and evaluated by light microscopy with hematoxylin and eosin and Masson trichrome staining, scanning electron microscopy, transmission electron microscopy, and immunocytochemical staining. Paraffin-embedded sections were stained with smooth muscle cell alpha-actin, which demonstrated smooth muscle cells in the pseudointima, and Ham 56 stain to identify macrophages. Endothelial factor VIII/von Willebrand factor and Ulex europaeus agglutinin identified human endothelial cells on the flow surface, in areas far removed from the anastomoses to the native vessels. This is the first definitive proof in a human of endothelialization of a synthetic arterial graft beyond the pannus ingrowth zone.

Isolation and biochemical characterization of a novel lantibiotic mutacin from Streptococcus mutans

Certain members of the indigenous biota of humans produce antimicrobial substances called bacteriocins, which inhibit other bacteria, including members of their own species. One of these substances, mutacin, is made by Streptococcus mutans, a member of the oral biota. Mutacin inhibits other mutans streptococci as well as many gram-positive exogenous pathogens. Here, we report for the first time the purification and partial biochemical characterization of a lanthionine-containing mutacin peptide from S. mutants T8. The biologically active peptide was isolated from the broth cultures by ultrafiltration and differential precipitation. The final mutacin preparation was homogeneous as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and N-terminal amino acid sequencing. A molecular mass of the peptide was estimated by electrospray ionization mass spectroscopy to be 3,244.64 +/- 1.15 Da. Its amino acid composition indicates the presence of lanthionine and likely beta-methyllanthionine in a total of about 25 amino acids. Because alpha,beta-unsaturated amino acids, the precursors of lanthionine residues, are often found in lantibiotics, we carried out the addition reaction of the mutacin with N-(methyl)mercaptoacetamide. The subsequent electrospray ionization mass spectroscopy analysis indicated the presence of two reaction products with M(r)s of 3,350.45 and 3,456.0. These are interpreted as the mutacin molecule with the addition of one and two molecules of reagent to the unsaturated amino acids, respectively. Sequencing of the peptide revealed an N-terminal amino acid sequence of Asn-Arg-Trp-Trp-Gln-Gly-Val-Val.

High-performance liquid chromatography-based assays of enzyme activities

Interest in using HPLC to assay enzymatic reactions continues to grow as evidenced by the more than 100 papers published during the early 1990s. HPLC can be used for any enzymatic assay that requires separation of substrates and products before quantifying the extent of the reaction. The popularity of HPLC-based assays is due to several reasons: (1) HPLC offers unsurpassed precision, specificity, sensitivity, and reproducibility. (2) Powerful microcomputers and user-friendly software automate the running of samples and collection and processing of data. (3) Current columns, especially C18 packings, separate a very wide variety of samples, and (4) A variety of on-line detectors provide a means to detect virtually any compound. This review surveys recent papers on the development of HPLC-based assays for enzymes that degrade or otherwise modify macromolecules. Methods for assaying enzymes involved in metabolic pathways are also reviewed. Work by the authors in developing HPLC-based assays for mitochondrial enzymes that use GTP/GDP and other nucleotides that cannot be or are not easily assayed by enzyme-coupled assays is discussed. These enzymes include nucleoside diphosphate kinase, succinate thiokinase, and GTP-AMP phosphotransferase. The assays are suitable for determining the submitochondrial compartmentation of enzyme activities. Finally, current and anticipated trends in HPLC technology, including new column packings and the trend toward smaller columns that give faster separations, are reviewed in relation to enzyme assays.

Culture of urethral fibroblasts: cell morphology, proliferation and extracellular matrix synthesis

The in vitro morphology and proliferative activity of urethral fibroblasts were characterized from primary isolates of fetal bovine urethral spongiosum. Cells were identified as fibroblastic based on their spindle-shaped morphology and lack of expression of phenotypic markers characteristic of either urethral smooth muscle or epithelial cells. Urethral fibroblasts proliferated at a steady rate and did not exhibit contact-inhibition of growth in a culture medium of Medium 199 supplemented with 10% newborn calf serum. Both immunohistochemistry and metabolic labeling analyses of extracellular matrix synthesis demonstrated the presence of collagen types I and III, and fibronectin. Quantitation of the collagenous components of the cell medium revealed that urethral fibroblasts synthesize 85% type I collagen, 14% type III collagen and < 1% type V collagen. In contrast, the urethral fibroblast cell layer matrix consisted of 98% type I collagen, < 1% type III and < 1% type V collagen.

Biochemical characterization and quantitation of the collagenous components of urethral stricture tissue

The collagenous composition of normal and strictured human urethral tissue was analyzed qualitatively by immunohistochemistry and quantitatively by 2-dimensional gel electrophoresis of cyanogen bromide digested tissue. Histological comparison of the normal and strictured urethral tissue showed that the normal urethral spongiosum was replaced by densely packed connective tissue fibers interspersed with fibroblasts in the strictured tissue. The immunohistochemical analysis of urethral tissue identified the presence of types I and III collagen fibers in normal spongiosum and in the connective tissue scar of strictured tissue. Estimation of the collagen type III:I ratio using scanning densitometry revealed a CB5:CB8 peptide ratio of 0.357 +/- 0.058 in the normal tissue, while the urethral stricture tissue had a CB5:CB8 ratio of 0.203 +/- 0.079 (p = 0.010). Total collagen content, as determined by hydroxyproline analysis, revealed no statistically significant differences between control and strictured tissue. Therefore, the normal urethral spongiosum was comprised of 75.1% type I collagen and 24.9% type III collagen. In contrast, the type I collagen in urethral stricture tissue was increased (83.9%), with a corresponding decrease in type III collagen (16.1%). This alteration in the ratio of collagen type III:I may explain the fibrotic noncompliant nature of urethral stricture scar tissue.

Atherosclerosis in young white males: arterial collagen and cholesterol

As part of a multicenter study on atherosclerosis, we examined defined segments of thoracic and abdominal aortas from 118 white males, age 15-34 years, who died from external causes. One half of each aorta specimen was graded for lesions. Intima-media preparations were assayed for collagen and cholesterol in two standardized regions (dorsal and ventral) derived from the alternate half of each segment. Even though the mean extent of intimal surface involvement with raised lesions remained minimal (0-6%), the data revealed a remarkable transition in vessel wall chemistry over this time span. For example, the amount of collagen per unit surface area increases with age in all vessel segments except the ventral domain of the thoracic aorta. The amount of collagen as a percent of total vessel protein rises with age only in the ventral and dorsal regions of the abdominal aorta. Free and esterified cholesterol levels per unit surface area increase with age in all vessel segments. There is a significant correlation between collagen and esterified cholesterol per unit surface area in all vessel regions with the exception of the abdominal ventral segment. In the latter segment increases in collagen per unit surface area occur without a corresponding increase in cholesterol level suggesting that connective tissue proliferation may actually precede lipid deposition in the genesis of atherosclerosis. Esterified cholesterol is present at higher levels in the dorsal domains of the thoracic and abdominal aortas than in the ventral domains. These findings provide chemical data confirming that the dorsal domains is the most lesion-prone region of these vessel segments.(ABSTRACT TRUNCATED AT 250 WORDS)